e course



Dry root rot - Macrophomina phaseolina(Sclerotial stage: Rhizoctonia bataticola)
The disease occurs both in young seedlings and grown up plants. Infected seedlings can show reddish brown discoloration at collar region. The lower leaves show yellowing, drooping and premature defoliation. The discolored area later turns to black and sudden death of the plants occurs in patches.
The bark near the collar region shows shredding. The plant can be easily pulled off leaving dark rotten root in the ground. Minute dark sclerotia are seen in the shredded bark and root tissues. Large number of brown dots seen on the stem portion represents the pycnidial stage of the fungus.
Macrophomina phaseolina- Symptoms 1
Macrophomina phaseolina- Symptoms 2

The fungus produces dark, brown, filamentous hyphae and constrictions are seen in hyphal branches at the junction with main hyphae. Sclerotia are jet black, smooth, hard, minute, globose and 110-130µm in diameter. The pycnidia are dark brown and ostiolated. Conidiophores (phialides) are hyaline, short, obpyriform to cylindrical, develop from the inner walls of the pycnidium. The conidia (Pycnidiospores) are hyaline, single celled and ellipsoid to ovoid.
Favourable Conditions

  • Prolonged drought followed by irrigation.
  • High temperature of 28-35˚C.

Disease cycle
The primary spread of the disease is by seed and soil. Secondary spread is by air-borne conidia. The pathogen survives as sclerotia in the soil as facultative parasite and in dead host debris.

  • Treat the seeds with carbendazim or thiram at 2g/kg or pellet the seeds with Trichoderma viride at 4 g/kg (106cfu/g).  
  • Apply heavy doses of farm yard manure or green leaf manure like Gliricidia maculataat 10 t/ha or apply Neemcake at 150 kg/ha.